The concept of Engineered Explosives is that it's a mystical bomb, infused with energy from several of the Mirrodin suns, that can selectively destroy certain objects but not others. You can see the "bomb" exploding in the foreground.
Note how all five suns are represented in the art (like all Sunburst cards). Note also how two loxodons in the background are blowing up, while the swordsman remains. It's possible that these explosives were set to 5, and are blowing up two 5-mana Loxodon Stalwarts while leaving unharmed a 2-mana Auriok Steelshaper.